w q o d b u r y



UNI STAT D. A. VOODBURY, OF ROCHESTER, NEGV A' rc.

YORK.

VARIABLE CUT-OFF GEAR FOR STEAM-ENGINES.

To alt whom it may concern:

Be it known that I, D. A. VVOODBURY, of Rochester, in the county of Monroe and State of New York, have invented a new and Improved Variable Cut-Off Gear for Steam-Engines; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure 1, exhibits a side view of the main valve gear, and cut-off gear of an engine, and a section of the valves and steam passages. Fig. 2, is a transverse section of the variable slide and the rocker to which it is attached.

Similar letters of reference indicate corresponding parts in both figures.

My invention consists in a certain arrangement of a rocker fitted with a variable slide, and o-f two connecting rods attached to the said slide, in combination with an eccentric or its equivalent and with the arms on the shafts of two cut-off valves, whereby I obtain a very simple and effective cut-off gear which is variable either by a hand adjustment or to serve as a regulator of the speed of the engine under the control of a governor.

, To enable others skilled in the art to make and use my invention, I will proceed to describe it.

The drawing shows the application of my invention to oscillating or rolling cutoff valves, but the invention may be applied to slide valves, as will be hereinafter explained. The main and cut off valves and steam passages are represented in blue colo-r to distinguish them from the cut-off gear which constitutes my invention.

A, A', are the main valves having secured on their central shafts ca, a', arms B, B', which are connected together by a rod C, and to the rod D', of the main eccentric D, in the crank shaft E, of the engine.

F, F', are the cut-off valves and 6,2),19', b', their ports, said valves having secured on their central shafts CZ, CZ', arms Gr, Gr'. These arms are connected by the two rods H, H', with the variable slide I, which is fitted to slide in a slot c, in the rocker J, which is arranged to rock on a shaft or fixed aXle K, arranged midway between the shafts Gr, Gr'. The length of the rocker and of the rods H` H', is such that the rods form a considerable angle with each other. The rocker J, is connected with the rod L, of an eccentric M, on the crank shaft E, and the variable slide is connected with a rod N, which may be supposed to be connected with any adjusting apparatus, or with a governor.

The position of the cut-off valves F F', relatively to their ports at any point in the stroke of the engine depends upon the position of the slide I, in the rocker J, as will be readily understood by comparing the relative positions of the said slide, the connecting rods and the valve arms Gr, G', as shown in red outlines with their relative positions as shown in black outlines in Fig. l, the position of the crank shaft and eccentric being the same in both cases. The eccentric M, is so set relatively to the crank that in the highest position of the slide I, in the rocker, the ports I), b, b', o', will be wide open at the commencement of the stroke.

rlhe main valve gear being of well known character, its operation needs no description. The cut-olf gear operates as follows. The rotary motion of the eccentric M, gives the rocker J, and its slide I, a movement once back and forth during every stroke of the engine, and by this movement of the slide the necessary rocking motion is imparted through the rods I-I, H', to the valve arms Gr, G', and the necessary rolling movement given to the valves F, F', to open and close the ports o, o. The closing of the ports is effected sooner or later in the stroke of the piston by raising or lowering the slide I, in the rocker J. By raising the slide the stroke of the valves is not only shortened but the valves are shifted in their seats by the toggle-like action of the rods H, H', so that the ports o, o, are covered during a greater portion of their movement, and they are caused to cut off steam earlier in the stroke of the engine as is illustrated in Fig. 1, by the representation of the positions of the valves in bold outline to correspond with the black outline of the valve gear, and in dotted outline to correspond with the red outline of the valve gear. In that figure the piston is supposed to be moving from left to right and the valve F, is consequently the one which is operating. It will be seen that in the position of the valve gear represented inlblack outline the said valve F, has not commenced to close the ports b, but in the position represented in red it has already closed them and cut off the steam. The range of the slide may be so long that in its lowest position the valves Will never close the ports Z), at all, and in its highest it would never open them.

In the application of this Crit-olin gear to slide Valves, the arms G, G', would be secured to two rock shafts, which might be connected with the valves in any known manner.

What I claim as my invention and desire to secure by Letters Patent, is-

The arrangement of the rocker J, and its Variable slide I, and the inclined or togglelike connecting rods H, H', in combination with the eccentric M, or its equivalent, and the arms G, Gr', on the valve shafts, substantially as herein described.

D. A. WOODBURY. lVitnesses ROBERT PEARsoN, H. D. SCRANTON. 

